Display board construction



May 18 1943 L. F. uRBAlN 2,319,278

DISPLAY BOARD CONSTRUCTION INVENTOR.

ATTORNEYA May 18, 1943 L F.l URBAIN 2,319,278

' DISPLAY BOARD CO-NSTRUGTION Filed Oct. 18, 1.9259l 3 Sheets-Sheet 2May 18, 1943 1. F. URBAIN 2,319,278

DISPLAY BOARD CONSTRUCTION M I Filed oct. 18. 19.39 :s sheets-sheet sATTORNEY-5,

Patented May 18, 1943 i UNITED STATES PATENT OFFICEV DISPLAY BOARDCONSTRUCTION Leon F. Urbain, Chicago, Ill. Application october 1s, 1939,sena1N0.299,925

18 Claims.

The present invention relates to a display board construction andparticularly to `a supporting frameconstruction and to certain elementsand combinations of elements comprising the frame construction fordisplay boards, blackboards, bulletin board, card panels and the like.

The present invention contemplates providing a display board supportingframe construction for mounting blackboards and similar constructionelements adjacent ithe sub-surface of a supporting Wall or partition.

The structural arrangement of relatively extensive but thin slabs ofslate and other blackboard materials presents serious problems, both inrespect to fthe original facility Of assembly and mounting, as Well asthe adequacy and permanence of support. It has hitherto been thepractice to provide a supporting layer or series of contact points ofsome suitable plaster in back of the blackboard element per se, and thento apply a retaining trim. Various'gripping means have been used toengage adjacent the periphery of each blackboard slab, While beingrigidly fixed to suitable ground strips. In each instance considerablediioulty is encountered in the initial assembly steps, Whereasdis-assembly for purposes of repair orreplalcement is even moredifficult. So, also, the normal variation in'thickness of the blackboardslabs inherent in the slatesplitting Operations has necessitatedextensive modifications in the prior prefabricated supporting elementswhere the outer surfaceof the board must be aligned in a carefullypredetermined plane.

lit is `an important object of the present invention to Overcome theforegoing difficulties lby providing a blackboard frame constructionreadily applicable to any suitable Wall or partition surface and whichfreely receives a blackboard or bulletin slab for holding the slabpositively [by means of resilient pressure.

It is la yet more specific object of the present invention to provide agro-und or frame construction such as the above adapted to be receivedpreferably flush with the outer surface of a iinished Wall, the groundIbeing provided with uniformly distributed yielding or springmembers toperipherally receive the black-board unit as Well as retaining keysfreely insertable into position to hold the board uniformly against theyielding spring cushions. In accordance with this arrangement,therefore, it will be apparent that having constructed the supportingground the blackboard slab is finally mounted lby merely disposing it inthe recess provided therefor and slipping the retaining keys intoposition.

It is a yet further object ofthe present inventionto provide an improvedground or framing vmemberconstructed for carrying out the' foregoingfunction and particularly such a construction unit adapted to receiveplaster to conceal its points of attachment with the partition or wall.The present invention further contemplates the provision of outer trimmembers resilienltly engageable With retaining clips formed so as tointernally grip adjacent Opposed lateral portions Off the trim at alltimes. 1` l Among other important objects of the present 'invention areto provide a combination Of yieldable slab supporting and backingmembers With a ground strip such that the spring members are 'positivelylocated by virtue of their yieldable engagement with the ground strip;to providel a blackboard `ground construction which, While holding theblackboard slab as above, is so constructed as to provide separatemqldmg '01- trim 'strips free from any holding or retaining function;and to provide a construction' eliminating Wall condensation,particularly at localized areas. Yet other and further objects Will bemore apparent from the following detailed description When-.consideredin connection with the acom- Fig. 4 is a detailed perspective View of` acorner of the blackboard of Fig. 3 illustrating one method of joiningthe head trim with a jamb.

Fig. 5 is a detailed, sectional View taken on line 5-5 of Fig. 3.

Fig. 6 is a perspective vieW of a spring clip for retaining the trim ormolding strip. Fig. '7 is a sectional, detailed View taken on line 'l-lvertically through the blackboard of Fig. 3.

Fig. 8 is a detailed, perspective View of the blackboard of Fig. 3,portions of the surface having been'freely broken away to show in detailthe internal construction and arrangement of the parts.

Fig.9 is a sectional vieW taken in a similar location as Fig. 7, butshowing a modified form of supporting channel.

Fig.'10 is a detailed, sectional view taken horizontally on line lil- Iof Fig. 7 to show the detailed construction and arrangement of theyielding spring supports for the blackboard slab.

Fig. 11 is a perspective, detailed view of the end of the chalk trayshowing in particular the construction of the end stop.

Fig. 12 is a perspective view of the end stop shown in dis-assembledrelationship.

Fig. 13 is a sectio-nal view taken vertically on line I3--I3 of Fig. 11to illustrate the means for joining the end stop to the tray.

Figs. 14, 15, 16 and 17 are perspective views of a map or supportingrail and slide construction which may be substituted for that shown inFig. 8.

Figs. 18 and 19 are sectional views taken vertically through the railand slide constructions shown in Fig. 17 on line I8-I8 thereof.

Fig. 19 further illustrates the removability of the slide.

Fig. 20 is a sectional, detailed view taken on line 20-20 of Fig. 16.

Fig. 21 is a sectional view taken centrally through an alternative formof trim strip.

Referring more particularly to the drawings wherein the presentinvention is illustrated more in detail, Figs. 1 and 2 disclose onepreferred form of display board construction comprising a ground orsupporting frame I0 receiving a blackboard slab I2 and also supporting achalk tray I4 and an appropriate trim or mold strip construction I6. Theground is mounted upon any suitable wall or partition I8 by means of anyIsuitable fastener 20. As shown in Fig. 2, the ground frame I 0 ispreferably mounted upon the surface of a sub-Wall or partition justbelow the plaster surface 22 so that the outer surface of the ground isultimately iiush with the surface of the plaster. With this constructionthe surface of the blackboard slab falls into co-planar disposition withrespect to the associated wall for the sake of. a more pleasingaesthetic appearance, as will hereinafter more fully appear, and thetrim strip alone projects outwardly of this plane.

Particular attention is directed to the construction of the so-calledground or frame and the structure of the strip material employed, forwhich purpose reference may be made to Fig. 8,.

which, while relating to an alternative embodiment of blackboardconstruction, nevertheless is formed from upper and lower ground stripsof identical construction. It will be noted that these ground membershave a central channel section provided by a flat, vertical wall surface24 and spaced, laterally extending walls 26 and 28, terminating in avertical flange parallel with the wall 24, and, therefore, parallel withthe final wall surface and with the plane of the blackboard. While theflange 30 may be apertured to receive fasteners 32 for engagement withthe sub-wall or partition, its function is primarily to support aplurality of yieldable springrnem.- bers 3S disposedv regularlytherealong. One'. of the spring members 35 (see Fig. 10) is composed ofa resilient, yieldable leaf gently and regularly curved at its centralportions and terminating in oppositely curved contact sections 38. Toreceive the yieldable spring supports 36 the flange 30 is struck out asat 4d to shift a predetermined tongue of metal laterally into parallelspaced relation while remaining integrally connected with the flange 36along one side edge only. Particular attention is directed to the factthat the formation of the struckv out portion results in an opposedrecess or aperture 42 adapted to receive the central, curved portion ofthe spring leaf 36. It will be accordingly obvious that when the springleaf is yieldably urged behind the struck out tongue 40 its central partsprings into the aperture 42 and positively retains the parts in theposition shown, whereas the curved portions 38 project outwardly t0receive the blackboard slate, as will hereinafter more fully appear.

The upper, lateral ange 25 of the ground strip Ill terminates in avertical attachment flange 44, similarly apertured to receive wallattachment fasteners 20. Here again it is important to note that theflange 25 forms an acute angle with the wall surface 24 which, incombination with the provision of a plurality of elongated apertures 48at the juncture with flanges 26, provides for the inter-lockingreception of the nal plaster surface 22.

The present ground strip construction provides simple and improved meansfor the positive retention of the blackboard slab against the yieldablecushioning springs in the form of a plurality of spaced locking keys orplates 50. Each of the keys or plates 50 in the present embodimentcomprises a flat sheet member beveled at its lower corners as at 52 tofacilitate entry into an engaging sheath or keeper 54 on the groundstrip, and has at its upper extremity, as Viewed in the upper portion ofFig. 8, laterally projecting ears or stops 56. rEhe engaging sheath 54is formed by striking out a portion of the area of the ground strip wall24 to a parallel plane sufficiently spaced to receive the thickness ofthe retaining plate 59. The struck out strap 54 remains integral withthe wall 24 at itslongitudinal extremities 58. It should be particularlynoted that each of the embracing straps 54 is disposed in longitudinalalignment with one of the foregoing yieldable spring units in suchposition that the extremity of the keeper or plate 5D projects oppositethe flange 30, as is clearly shown in Figs. 2 and 8. The foregoingcooperating elements confine, restrain and completely support theblackboard slab I2. Only the simplest of assembly operations areinvolved in arranging the periphery of the slab I2 against the regularlydisposed yielding supports 33, shifting the blackboard rearwardly andthen locking it in place by merely slipping the keeper ngers 50 throughtheir retaining sheaths and into engagement with the front surface ofthe board.

The foregoing strip construction which I provide in accordance with thepresent invention may be arranged in the form of a rectangular ground bycutting head, base and jamb pieces of the proper length and fasteningthese to the partition in the rectangular arrangement shown. The cornersmay be mitered, as shown in Fig. 1, or may be alternatively joined byany suitable connecting coupling block or insert. Upon completion ofplastering the ground thus formed provides a rectangular recess for thereception of the rectangular slab i2. rihere is provided, in accordancewith the construction shown in Fig. 1, an insulating and preferablysound-proof layer 68 which, in accordance with my observations,eliminates condensation and drumming. While any suitable insulating andcushioning or soundproof board may be employed, I prefer the use of anyof the well-known insulating quilts, such as those made of wool shoddyor other layers known as Capots quilt. It is preferred that the quilt beso disposed as to exert no 'urge the feather edge 93 intoi pressure lineconappreciable pressure against the surface of the blackboard.

The trim construction I6 is formed of a plurality of strips having achanneled section with oppositely inturned edges 62, as shown in Fig. 2,embracing the opposite extremities of a retaining clip 64. The clip v64,shown in detail in Fig. 6, has a bowed central portion and oppositelateral margins conflgurated with rounded,

beaded sections 66. A central slot'68 permits vattachment to the centralwall or web 24 of the ground strip by means of any self-threadingfastener 1I). It is` vimportant to lnote, as clearly shown in Fig. 2,that the trim strip, when pressed over the clip 64 resiliently engagesboth of the resilient beads 66. At all times, therefore,

'the beads exert an opposite yieldable, internal pressure against thetrim strip so that loosening or vibration is impossible.

- -The trim strip is cutin lengths corresponding to the jambs andheadstrip of the ground, and the corners may be mitered, as shown inFig. 1, or else brought into abutting inter-engagement with a cornerblock 'I2 co-extensive in sectional proportions with the trim strip andhaving projecting rails or lugs 'I4 receivable within the central,longitudinal recess thereof.

In the embodiment shown in Figs. 1 and 2, the lower trim function iseffected by the chalk trough I4. ,The details of construction of this.trough appear more particularly in Figs. 2, 5, 8, 11, 12 and 13, towhich reference is now made. -With the exception of a pair of end stops16, the trough is composed of a continuous length of extruded materialhaving a uniform section, indicated in Fig. 2.

It is to be particularly noted that the trough I4 has an uppersupporting surface I8 which is inclined outwardly at a substantial anglesufficient so that chalk dust will gravitate downwardly or to theright,as viewed in Fig. 2. The surface is provided with a plurality ofserrations or ridges 86, the lowermost serration defining a chalk groove82 together with an upwardly extending loop portion of the rail sectiondesignated at 84. Attention is particularly directed 4to the fact thatthe loop or abutment section 84 extends reversely with respect to thedownward inclination of the upper supporting surface to provide a stopor abutment for the eraser, as

lower portion. The upper extremity of the' trough similarly has asubstantially vertical flange portion 92 which, due to the inclinationof the supporting surface, forms a sharp, acuteA A section of the troughangle therewith. Particular attention is directedjV to the fact that therear surface of the flange 92 makes an angle with the verticalexemplified in Fig. 5 by the letter B. A so-called feather edge 93 isthus provided for making a line pressure tact with the' surface of theboard I2, while the lower bead 66 engages'behind flange extremity 90.For assembly purposes the flange 92 isy merely engaged behind the spring96 and the flange 90 clipped over the bead 66. The end stops 'I6 shownin Figs. 11, 12 and 13 comprise a vertical end wall 98 having laterallyextending margins projecting into congruity with the walls of the chalktrough. As more clearly shown in Figs. 11 and 13, the laterallyextendingupper surface portion continuous with the supporting surface ofthe trough is recessed slightly as at |60 to provide a guideway or spoutconfiguration for dust pro- `jected longitudinally across the extremityvof the trough. The facility with which the dust in the trough may beremoved is evidenced by the fact that the cleaning device may be movedlongitudinally in the lower groove 82 to direct the dust over the endstop into a suitable receptacle.

The end stops are provided with a plurality of lugs |62 engageableinteriorly of the walls of the trough and adapted to receive fastenings|04.

Where the lower trim or mold is desired in addition to the trough, acompound base-ground construction is provided, as shown in Fig, 5, inwhich a second ground strip |06 is located above the ordinary base stripand provided with struck out lugs 40 mounting pressure clips 36identical to those hitherto described. Strip |96 is otherwise providedwith an outer, central wall 24a and a lateral wall 28a, the latterterminating in a vertical ange 30a which mounts the tongue and clipspring construction. It is to be noted that the lower flange 26a definesthe lateral margin of the strip to facilitate nesting with the lowerground strip I0, as clearly shown in Fig. 5. Vertical alignment of thecompound base-ground construction is positively maintained by a pinwhich may be an ordinary nail or driven fastener |98 disposed invertically aligned apertures in the flanges 26a and lateral wall 28a andextending into a longitudinal slot III) in the upper lateral flange ofthe base ground strip. In accordance with this construction, the springclip 94 supports the chalk trough upon the upper base ground |36whereasthe lower ground mounts the spaced clips E4 which retain thelower trim strip IB. It will be seen that the lower, horizontal surfaceportion 88 of the trough thus cooperates with the upper, flat surface ofthe trim strip to reside in flatwise abutment. 'A

I have shown in Figs. '7 and 8.a modified form of board construction`embodying an indicia re ceiving slab I2 and in combination therewith abulletin board I|2 for receiving posted bulletins, The boards or slabsare spacedby a horizontal ground strip I I4 equivalent in configurationwith the foregoing strip I0 but havingupper and lower inner, verticalflanges 39a mounting pressure clips 36 in struck out tongues .40.. Theboard slabs are retained-against the pressure clip foundation by anouter display rail I IB secured to the ground I I4 by thread forming ortapping fasteners I I8. The rail is of simple channel configuration, asshown, having in-turned, marginal flanges I2!) to retain a plurality ofslidable display fixtures or blocks |22.

The interengagement of the vblocks with the supporting rail is shown indetail in Fig. 18 wherein it will be noted that to the rear of achamfered outer periphery |24 each block is provided with horizontalupper and Alower grooves or slots |26 and |28, respectively, (see Fig.19) which grooves receive the in-turned flanges |26 of thev guide rail.The lower groove |28y is rendered relatively shallow by relieving as at|30 a portion of the rearward Wall defining the slot I 28. Each block,while thus slidably interengaged with the guide rail, is freelyremovable, as shown in Fig. 19, when shifted upwardly to dislocate thelower ange from the groove |28.

The slidable fittings |22 shown in Figs. 17, 18 and 19 are centrallyapertured and counter-bored to receive a central plug or insert |32which may be formed of cork or similar soft material for lreceiving sucha fastener 'as a thumb tack. It is to be noted that the rearward facesof each of the blocks are relieved by a horizontally-extending groove|34 to permit the blocks to clear any projecting portions of thefasteners 0.

In accordance with the modied construction shown in Fig. i4, the blocks|22 are provided with hooks |36 projecting outwardly to suspend maps.

In a yet further modified embodiment, shown in Fig; l5, the blocks |22are provided with spring clips |38 comprising base strips |40 fixedrigidly upon the block. In using these clips the upper edges of papersor maps may be suspended by clipping them under the yieldable portions|33. It will be evident that in each instance any number of slidingblocks |22 may be provided longitudinally at will to provide the desirednumber of supporting points.

A further modification which I have shown for illustrative purposes inFigs. 16 and 17 comprehends the provision of adjustable supports for aroller suitable for mounting and supporting roller mounted maps and thelike. In accordance with this construction, each of the blocks |22 isprovided with brackets |44 for receiving the roller |46. Each bracket isrigidly held in each block |22 by fasteners |48 (see Fig. 20). I havediscovered that it is desirable and sometimes important to positivelydetermine the spacing of each pair of brackets when supporting a roller.To this end I supply for each block |22 a knurled thumb screw |50threadedly received in the block and bracket for frictional engagementwith the rear face of the guide rail or channel H5. While the thumbscrew is normally rotationally retracted to permit sliding adjustment ofthe blocks when arranged in the desired position, the screw may betightened to locate the unit in position.

It will be evident from the foregoing that my guide rail IE6 may besubstituted for the upper or head trim I6 in any of the foregoingembodiments where elevated bulletin means are desired and I have shownin Fig. 9 a modification adapted peculiarly for this purpose anddesignated by reference numeral |54. It will be seen that the rail |54is conigurated adjacent its rearward portions substantially identicallywith the trim I6 for engagement upon retaining clip 64. In accordancewith the present embodiment, the forward portion of the rail is providedwith a pair of spaced channel sections ISE and |58 separated by acentral partition wall |00 terminating in a transverse, oppositelyextending flange |62. The lower guideway or channel may receive anysuitable blocks |22, as hereinbefore mentioned, while the upper channelmay be, and is in the embodiment shown, caused to embrace a strip ofcork or similar material adapted to receive tacks for fastening.

I have disclosed in Fig. 2l one illustrative modification of the trimstrip to clearly illustrate and exemplify some of the Awide variationspossible in'accordance with the practical and aesthetic demands. Ingeneral, the trim shown in section in Fig. 1 differs from the trim stripI6 in providing a curved, outer wall |52.

Where a bulletin receiving or posting board H2 is employed, it issupported by pressure springs 36. In accordance with the illustratedembodiment of Fig. 8, it is preferred that some rigid backing beprovided in any conventional manner.

Throughout the specification and claims it will be evident that the termdisplay board or blackboard slab is intended to be used to cover notonly surfaces adapted to receive indicia by marking, but also othersupporting boards, particularly those adapted for wall display purposes.In other words, the term includes blackboards, bulletin boards andscreens of various types such as are employed in class rooms, marketsand the like.

From the foregoing it will be evident that the present inventionprovides for the rapid assembly and erection of such blackboard unitsfrom stock parts which may be cut to length for any particular job.After the erection of the ground by merely fastening four marginalground strips to the sub-wall, permanent mounting of the board iseiTected by urging the display board against the yieldable, peripheralspring seats in the recess thus provided and associating the latches orkeys 50 within each sheath provided therefor. The board is at this timepositively aligned in iiush relation with the outer plane of the groundand accordingly with the outer surface of the finished Wall. At thistime the clips 64 are applied and the trim strips snap into position tocompletely conceal underlying supports.

It is thought obvious from the foregoing that the present constructionprovides substantially theoretically ideal conditions for mounting slabshaving the peculiarities characteristic of blackboards. Thus the slab,While positively positioned, is, nevertheless, held by a carefullypredetermined pressure at points regularly peripherally spaced.Compensation is thus made for the unavoidable and usual variations inthe thickness of the slab or any changes which may occur, and theelement is ideally supported for yresistance to shock or vibration. Aspointed out previously, the present invention provides an insulationwhich solves the structural problems known as wall condensation anddrumming.

It is further important to note that the present chalk trough assemblypositively accumulates chalk dust which normally might settle Withininternal crevices by directing these particles on to the downwardlyinclined receiving surface of the trough and to a receiving grooveprovided therefor. The eraser in spaced relation to the receiving groovethus rests upon a supporting surface relatively clean and free of dust.

Of even greater importance, however, is the fact that the chalk trough,because of its inclined position, presents the eraser at all timesfacing the student who, being normally in front of the blackboard,directs his attention toward the eraser trough at a downward angle. Thusthe eraser is not only in plain view and more easily accessible but, atthe same time, is spaced and located a substantial distance from theblackboard. It will be realized that this is of great practicalsignificance in view of the objectionability of contacting the lingersand particularly the finger nails with a slate or similar surface orwith associated molding, as has hitherto been `the `frequent case.

With the present construction the eraser will always gravitatedownwardly to the abutment rail 84 in a position where it is instantlyaccessible and free from inadvertent undesirable contact with theblackboard.

It is further of great importance to note that the foregoing knife edgelip construction 93 making a line contact with the blackboard providesan integral dust deflector whereby all falling and settling chalk dustis directed downwardly into the receiving groove 82 provided therefor.This provides a clean, sanitary constructi-on as opposed to those priorconstructions wherein the objectionable and pathologically harmful dustparticles were normally permitted to collect within or adjacent the trimor other portions of the blackboard assembly, either internally orexternally, wherein they could not be cleaned away and removed.

Another important new result iiowing from the inclined supportingsurface configuration of the foregoing chalk trough resides in thefacility with which this surface may be abuttingly associated with thetrim `and other strips. Thus it should be noted that the angle of theeraser supporting or dust deecting surface is equal to 45 degrees.Therefore, when assembling blackboard constructions, such as shown inFig. 1, in which the side trim strips abut the chalk trough at theirlower extremities, it is merely necessary to cut or miter the lowerextremity of each of the side strips to 45 degrees, as shown in Fig, 2,in order to secure a perfect t. Thus the side trim strips may be cut tosize on any ordinary miter box equipment, having the conventional meansfor cutting a 45 degree angle.

It i-s thought that the invention `and numerous of its attendantadvantages will be understood from the foregoing description and it isobvious that numerous changes may be made in the form, construction and'arrangement of the several parts without departing from the spirit orscope of the invention, or sacrificing any of its attendant advantages,the form herein described being a preferred embodiment for the purposeof illustrating the invention.

The invention is hereby claimed as follows:

1. A building construction for supporting a display board or the like,comprising a ground strip defining a wall recess, said ground stripmountingva display board in said recess, peripherally-spaced pressuremeans interiorly of said recess, and means operatively mounted formovement in the plane of said display board and transversely to the saidground strip and being constrained for shiftable movement in said pathto extend across said recess for holding a display board against saidpressure means in predetermined relationship thereto.

2. A building construction for supporting a display board or the likecomprising a ground strip defining a wall recess, said ground striphaving flange portions extending into said recess and permanentlymounting yieldable, outwardly-projecting pressure members at spaced,peripheral points, means for retaining a display board positively withinsaid recess andin pressure engagement with said peripheral pressuremeans, said retaining means comprising a holding member operativelymounted on said ground strip for movement in a fixed predetermined pathin the plane of said display board and in a direction transversely ofsaid strip, said hold-A ing member being constrained against movement inall other directions in said path, said hold- Ying member having aportion adapted to extend outwardly from the strip and across thevrecess in one position of the holding member to overlie the outer faceof the display board.

3. A building construction for supporting a display board or the likecomprising a ground construction dening a wall recess and comprising aplurality of marginally arranged strips, at least one of said stripshaving an outer portion, guide means associated with the outer portionand extending transversely of said strip, a Aholding member constrainedfor sliding movement within said guide means in a direction transverselywith respect to said strip and having an extension operative in oneposition to extend across the margin of said recess to retain a displayboard located therein, and yieldable pressure means within said recessfor applying to a display board retained by said keeper means.

4. A construction element comprising an elongated ground strip having anouter surface, a lateral wall associated with said outer surface andsupporting an inner flange in spaced, generally parallel relationship tosaid outer surface, resilient, freely-yieldable pressure means mountedon said liange for applying a yieldable pressure to the inner peripheryof a display board, and a laterally extending guideway in associationwith said outer Wall and extending transversely of the stripsubstantially in the plane of the outer wall for slidably accommodatinga holding member.

5. A construction element comprising an elongated ground strip having anouter surface, a lateral wall associated with said outer surface andsupporting an inner flange in spaced, generally parallel relationship tosaid outer wall, resilient, freely-yieldable pressure means mounted onsaid flange for applying a yieldable pressure to the inner periphery ofa display board, and a lateral guideway in association with said outerwall and extending transversely of the strip substantially in the planeof the outer wall for slidably accommodating a holding member, saidguide means and pressure means being disposed in substantiallylongitudinal alignment along the strip.

l 6. A construction element for use in the assembly of a display boardground comprising an outer wall, an inner wall laterally offset fromsaid outer wall, and means on said inner wall for receiving a pressurespring, said means comprising a tongue laterally offset in a spaced,parallel plane yand providing an aperture in Said inner Wall oppositesaid tongue for receiving the central portion of' said spring.

7. An elongated construction element for use in the assembly of adisplay board ground comprising an outer wall, an inner wall laterallyoffset from said outer Wall, a pressure spring receiving means on saidinner wall and comprising a tongue struck out of said wall and laterallydisposed in a spaced, parallel plane and providing an aperture in saidinner wall opposite said tongue for receiving the central portion ofsaid spring, said struck out portion being integral with said last-namedwall adjacent one side edge only whereby a yieldable pressure spring isyieldably disposable within said recess.

8. An elongated construction element for use in the assembly of adisplay board ground comprising an outer Wall, an inner wall laterallyoffset from said outer wall, a pressure spring receiving means on saidinner wall and comprising a tongue struck out of said wall and laterallydisposed in a spaced, parallel plane and providing an aperture in saidinner Wall opposite said tongue for receiving the central portion ofsaid spring, and yieldable pressure means comprising a leaf springhaving a curved, central portion disposed beneath said struck outportion and extending within said recess, and yieldable extensionsprojecting outwardly away from said last-named wall and yieldable towardsaid wall under predetermined pressures, said yieldable extensions beingformed to resiliently engage side margins of the tongue to hold thespring in operative position when initially assembled.

9, An elongated construction element for use in the assembly of adisplay board ground comprising an outer wall, an inner wall laterallyoiTset from said outer wall, a pressure spring receiving means on saidinner wall and comprising atongue struck out of said wall and laterallydisposed in a spaced, parallel plane and providing an aperture in saidinner wall opposite said tongue for receiving the central portion ofsaid spring, and a struck out keeper portion formed on said outer walland integral with said outer wall along longitudinally disposed sidesfor freely, slidably guiding a latching member in spaced relation tosaid tongue.

10. A construction element for use in the assembly of a display boardground upon a supporting partition and comprising an elongated, outerWall adapted to be disposed substantially in the plane of the outersurface of said partition, a marginal attachment iiange inwardlydisposed with respect to said outer surface, and a lateral wall joiningsaid attachment flange and outer wall, said lateral Wall being disposedin a plane inclined inwardly of said margin of the outer wall and makingan acute angle with said outer wall for interlocking engagement with aplaster coat.

11. A construction element for use in the assembly of a display boardground upon a sup,- porting partition and comprising an elongated, outerwall adapted to be disposed substantially in the plane of the outersurface of said partition, a marginal attachment flange inwardlydisposed with respect to said outer surface, and a lateral wall joiningsaid attachment iange and outer wall, said lateral wall being disposedin a plane inclined inwardly of said margin of the` outer wall andmaking an acute angle with said outer wall for interlocking engagementwith a plaster coat, said lateral wall being provided withlongitudinally disposed, plaster receiving apertures.

12. A retaining abutment member adapted to positively position a displayboard with respect to a ground comprising a substantially flat platevhaving spaced generally .parallel laterali side margins, convergingadjacent one extremity to, facilitate entry within a guideway and havinglateral projections projecting outwardly of said side margins oppositethe other extremity to locate the plate with respect to the guide, and aground member for attachment to a supporting wall, said ground memberhaving an outer face disposed generally in the plane of said wall and aguideway formed thereon and extending transversely of the ground memberin said plane for complementarily receiving the abutment member, saidguideway and abutment member being proportioned and arranged to providea section adapted in one position of the across the .margin thereof tooverlie the outer face of an adjacently positioned display board.

13. In combination, an elongated structural element adapted for assemblyupon a supporting partition to provide a display board ground, saidstructural element having an outer wall and extending transversely ofsaid elongated member in the plane of said wall, a guideway on saidwall, and a display board retaining member adapted to be slidablyreceived in said guideway, said guideway positively guiding saidretaining member in said transverse direction, said retaining memberbeing constrained against movement in all other directions whilereceived by the guideway, said retaining member having a portion adaptedto extend outwardly from the strip and beyond a lateral side margin ofsaid outer Wall to overlie the outer face or" a display board.

14. In combination, an elongated structural element adapted for assemblyupon a supporting partition to provide display board ground, saidstructural element having an outer Wall and extending transversely ofsaid elongated member in the plane of said wail, a guideway on saidwall, and a display board retaining member adapted to be slidablyreceived in said guideway, said guideway positively guiding saidretaining member in said transverse direction, said retaining memberbeing constrained against movement in all other directions whilereceived by the guideway, said retaining member in one slidable positionextending substantially beyond the margin of said outer Wall, and amarginal flange substantially inwardly disposed with respect to saidouter wall and supporting, yieldable pressure means in juxtaposition tosaid extremity of said retaining keeper.

15. An elongated construction unit adapted to provide a compound groundstructure for supporting a chalk trough in juxtaposition to a trim, saidelongated construction element comprising an outer, wall surfacearranged in a substantially flat plane, lateral, marginal flangeportions disposed longitudinally of said outer, :dat wall surface, andextending on one side, of the plane of said surface, one of said ilangessupporting an attachment flange in spaced relationship to the plane ofsaid outer wall, the other lateral, marginal iiange extending toward butterminating short of the plane of said attachment flange, and aperturesin said lateral flanges and aligned in a plane parallel to the plane ofsaid outer wall for receiving a locating pin.

i6. In a display board construction comprising a ground mounted upon asupporting Wall and defining a recess, a display board in said recess,yieldable pressure means peripherally located in sail recess for urgingsaid board outwardly, and a continuous uninterrupted layer of insulatingmaterial located between said display board and the supportingpartition.y

1'7. A resilient spring clip for releasably securing trim strips to adisplay board ground construction, comprising a central portion arrangedin a laterally curved plane having a convex side and a concave side,said clip terminating in free lateral side margins formed withlongitudinally extending bead congurations, said bead configurationsprojecting` inwardly toward the convex face of said clip for engagementbyreversely extending margins of a trim'strip, and means,

being relatively deep, said recesses being spaced so that the upper riboccupiesonly a portion of the depth of the upper recess and provides anadditional portion therebelow at least equivalent to the depth of thelower recess, said block being shiftable upwardly with respect to saidrail lto a position Where the lower recess is disposed beyond said lowerlip and freely disengageable therefrom whereby the block is separablefrom said lower recess being relatively shallow with 1G said rail.

respect to the lower lip and said upper recess LEON F. URBAIN.

